1.Action 代码
/*
* $Id: ShowFileAction.java 471754 2006-11-06 14:55:09Z husted $
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
*
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.struts.webapp.validator;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.InputStream;
import java.io.InputStreamReader;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.commons.logging.LogFactory;
import org.apache.commons.logging.Log;
/**
* Action which retrieves a file specified in the parameter
* and stores its contents in the request, so that they
* can be displayed.
*/
public class ShowFileAction extends Action {
/** Logging Instance. */
private static final Log log = LogFactory.getLog(ShowFileAction.class);
public ActionForward execute(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws Exception {
// Get the file name
String fileName = mapping.getParameter();
StringBuffer fileContents = new StringBuffer();
if(fileName != null) {
InputStream input = servlet.getServletContext().getResourceAsStream(fileName);
if (input == null) {
log.warn("File Not Found: "+fileName);
} else {
InputStreamReader inputReader = new InputStreamReader(input);
char[] buffer = new char[1000];
while (true) {
int lth = inputReader.read(buffer);
if (lth < 0) {
break;
} else {
fileContents.append(buffer, 0, lth);
}
}
}
} else {
log.error("No file name specified.");
}
// Store the File contents and name in the Request
request.setAttribute("fileName", fileName);
request.setAttribute("fileContents", fileContents.toString());
return mapping.findForward("success");
}
}
分析：
String fileName = mapping.getParameter();
其中mapping 是ActionMapping 对象，是ActionConfig的子对象。 其中ActionConfig封装了Struts-config.xml 中的配置信息。
inputStream input = servlet.getServletContext().getResourceAsStream(fileName);
每个Web应用程序都是一个独立的Servlet容器，每个Web应用程序分别用一个ServletContext对象。ServletContext对象包含在ServletConfig对象中，
调用ServletConfig.getServletContext()方法获取ServletContext对象。
1、 getResourcePath 返回一个包含该目录和文件路径名称的Set集合
2、 getResource 返回映射到资源上的URL对象。
3、 getResourceAsStream 返回连接到某资源上的InputStream对象
InputStreamReader inputReader = new InputStreamReader(input);
需要重新包装成字符处理。
【2】配置文件
"/showValidation"
type="org.apache.struts.webapp.validator.ShowFileAction"
scope="request"
parameter="/WEB-INF/validator/validation.xml">
"success" path="/showFile.jsp" />
通过传递不同的parameter，读取不同的文件。
【3】在JSP页面 读取信息
"white">
File: "fileName" scope="request" />
"fileContents" scope="request" filter="true"/>
bean:write 标签 有个filter属性。如果为true 的话，则表示
将把输出内容中的特殊HTML符号作为普通字符串来显示；如果filter属性为false,则不会把输出内容中的HTML符号转化为普通字符串．
